The present invention relates to the manufacture of helicoidal springs and is concerned more exactly with a machine to form the springs and control apparatus for the machine.
Machines for winding springs comprise, as is known, a bar-mandrel for winding of the springs mounted in a rotatable broach which is mounted in a movable carriage for longitudinal displacement. The movable carriage is moved on a base and is driven by a rotating drive screw which by disconnectable means controls the movement of the carriage and consequently the pitch and number of turns of the spring. The precise type of the spring consequently depends upon the helicoidal groove of the drive screw used. If the manufacturer wishes to manufacture different types of springs a range of drive screws must be employed corresponding to the range of springs to be manufactured. This is a great inconvenience because of the difficulty in obtaining a drive screw provided with accurate grooves which is quite costly and on the other hand because of the shut-down time of the machine required for the replacement of the drive screw.
Another inconvenience of machines generally utilized is in the disconnectable means which connects the carriage to the drive screw which means generally are made up of a threaded nut closing on the drive screw which maneuver is often time consuming to carry out and inaccurate.